1. Technical Field
This application relates to bipolar surgical instruments and, more particularly, to bipolar surgical forceps having a cutting blade for selectively grasping, manipulating, cutting and coagulating body tissue.
2. Background of Related Art
Electrocauterization involves the sealing of blood vessels and/or the coagulation of blood and other fluids which are capable of coagulation by the application of a high frequency electrical current. In bipolar electrosurgery, a high frequency power supply is connected to the bipolar instrument and an electrical current is applied through an electrode which contacts the body tissue to be treated. A return electrode is placed in contact with or in close proximity to the current-supplying electrode such that an electrical circuit is formed between the two electrodes. In this manner, the applied electrical current is limited to the body tissue held between the electrodes. Current passing from one electrode to the other produces heat sufficient to seal the blood vessels in tissue or to coagulate blood and other fluids capable of coagulation. Each electrode of the bipolar instrument is electrically isolated within the instrument and is separately connected to the power supply. Typical power supplies such as the SSE2L.TM. available from Valleylab, Inc. of Boulder, Colo., are r.f. generators which can produce different electrical wavefronts to effect coagulation. When the electrodes are separated from one another, the electrical circuit is open and thus inadvertent contact of body tissue with either of the separated electrodes does not cause current to flow.
Electrosurgical procedures have, in recent years, become increasingly widespread. The ease and speed of coagulating tissue saves the surgeon valuable time while minimizing internal bleeding by the patient. Endoscopic and laparoscopic surgical procedures have created additional incentives for the use of electrosurgical techniques. In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision; in endoscopic procedures, surgery is performed in any hollow viscus of the body through narrow tubes inserted through small entrance wounds in the skin. Because laparoscopic and endoscopic surgery does not bring the surgeon into direct contact with the operation site, internal bleeding must be quickly controlled by instruments easily operable from a remote location. Electrosurgical instruments provide the surgeon with the ability to coagulate tissue such that bleeding is minimized and to effectively seal off bleeders during laparoscopic and endoscopic procedures. Because laparoscopic and endoscopic surgery involve instrument manipulation from a remote location, the actuating mechanism must be convenient to operate once the instrument has been properly positioned.
Several configurations have been proposed for bipolar electrosurgical instruments particularly adapted for treating tissue. Bipolar knives are described in U.S. Pat. Nos. 4,161,950 and 4,232,676. In these patents, two or more separated, fixed electrodes are disposed on the surface of a ceramic blade. These electrodes are used to cut and/or coagulate tissue when electrical current passes through tissue positioned between a pair of these fixed electrodes.
Another bipolar electrosurgical instrument is the bipolar forceps. This instrument, examples of which are described in U.S. Pat. Nos. 3,643,663, 4,003,380, 5258,006 and 5,342,359 is used to treat tissue held between the conductive forceps jaws. Current flows through tissue held between the forceps jaws to effect coagulation of the tissue.
Other designs for bipolar forceps have been proposed. In U.S. Pat. No. 5,151,102, a sintered, insulating blood vessel contact member is provided on stainless steel or titanium forceps. Exposed electrodes of a conductive resin are disposed over the surface of the vessel contact member.
The product literature for EVERSHEARS.RTM., available from Everest Medical Corporation, Minneapolis, Minn., describes laparoscopic scissors. Ceramic blades and a single-action dissecting tip are illustrated.
Once the tissue has been coagulated and any bleeders have been effectively sealed off, it is often desired that the tissue so coagulated be severed at the site of the coagulation. Bipolar forceps, while capable of burning through tissue, do not shear the tissue in a clean-cut fashion. Bipolar scissors, on the other hand, while capable of shearing tissue, usually do so at the same time coagulation is occurring, which often results in incomplete coagulation of the tissue. U.S. Pat. No. 5,342,381 to Tidemand describes a combination bipolar scissors and forceps instrument which is capable of performing as both a bipolar forceps and a bipolar scissors. However, when performing as a bipolar scissors it does not eliminate the problem of simultaneous shearing and coagulation. In addition, because the combination scissors and forceps are positioned on the same member, tissue which is not intended to be cut may inadvertently contact the shearing portion of the member.
At present, surgeons who desire to coagulate and cut tissue will usually employ an electrosurgical forceps to coagulate the tissue and then proceed to cut the tissue by utilizing a conventional endoscopic scissors, such as the Endo Shears.TM. instrument available from United States Surgical Corporation, Norwalk Conn. This requires either the removal of the electrosurgical forceps from the surgical site in order to introduce the endoscopic scissors, or the introduction of the endoscopic scissors through an alternate port, with the surgeon exercising care not to contact the electrically conductive forceps with any conductive portion of the shearing instrument.
A need therefore exists in the art for a bipolar electrosurgical instrument which is capable of first coagulating tissue and then cutting the coagulating tissue without removing the bipolar instrument or inserting additional instrumentation. A need also exists in the art for an improved bipolar electrosurgical instruments in which coagulation and cutting are not simultaneous function, but which may be performed independently of each other with ease.